Well packers



Feb. 13, 1962 Filed NOV. 19. 1958 B. P. NUTTER 3,020,959

WELL PACKERS 4 Sheets-Sheet 1 Hls ATTORNEY B. P. NUTTER WELL PACKERS Feb. 13, 1962 4 Sheets-Sheet 2 Filed NOV. 19. 1958 FIG.8

FIGI.7b

FIG.7o

INVENTOR. BENJAMN P. NUTTER ms ATTORNEY Feb. 13, 1962 B. P. NUTTER 3,020,959

WELL PACKERS Filed. Nov. 19. 1958 4 Sheets-Sheet 3 .95' ATTORNEY Feb. 13, 1962 B. P. NUTTER 3,020,959

WELL PACKERS Filed Nov. 19, 1958 4 Sheets-Sheet 4 l INVENTOR. en/om/n f3. /Vc/zzer BY @Mc/74M A WLR/v5 y United States Patent 3,il2ll,95'9 Patented Feb. 13, 1962 The present invention relates to well packers and, more particularly, to a full opening casing packer useful in performing a plurality of operations with only one trip of the tubing string into the well.

It has heretofore been customary to use a separate tool and associated packer for each of Ithe operations of testing, acidizing, fracturing and squeeze cementing, thus necessitating pulling the tubing or drill spring for each change of tool. With the continued trend toward drilling to even greater depths, it has become increasingly desirable to reduce rig time by utilizing multiple purpose tools to perform a plurality of operations with only one trip of the tubing or drill string into the borehole.

A multiple purpose packer useful for any one or combination of Ithe above-enumerated operations must combine a number of features essential to each of the operations. For example, a well packer for use wtih a formation testing tool should be capable of remaining packed off against higher pressures from above in the well annulus and should not be affected by pushes and pulls applied to the tubing string to operate the testing valves. On the other hand, a well packer for use in acidizing, fracturing or squeeze cementing should be capable of remaining packed off against higher pressures within and below the tool. Moreover, a multiple purpose packer should preferably be full opening to enable treating with large fluid volumes and to enable passage of a small diameter perforating gun or other well tool. It is further desirable if the packer is left in the hole as a production packer that the packer resist pushes and pulls applied to the tubing string yet be adapted to be removed if desired.

An object of this invention, therefore, is to provide a new and improved well packer incorporating the aboveenumerated features adapting it for use in testing, acidizing, fracturing and squeeze cementing operations.

Another object of this invention is to provide a new and improved well packer incorporating the above-enumerated desirable features adapting it for use in testing, acidizing, fracturing and squeeze cementing operations or any combination thereof with only one trip of the tubing string into the well.

Yet another object of this invention is to provide a new and improved multiple purpose well packer which is full opening to permit passage of a gun perforator or other well tool and to enable treating with large fluid volumes.

A still further object of this invention is to provide a multiple purpose well packer having by-pass valve means, which packer and by-pass valve means cannot be unseated or opened simply by applying tension or compression to the tubing string.

These and other objects are obtained by a well packer including a tubular mandrel assembly received within a tubular housing assembly for relative movement with a tubing string between longitudinally spaced upper and lower positions. The tubular mandrel assembly has an axially extending central passage of sufficient diameter to enable passage of small diameter Well tools, such as a perforating gun. The housing assembly includes an upper housing member, an elastomer packer element, slip means and a lower housing member. The slip means includes portions coupled to the packer element and coupled to the lower housing member where one of the slip tion;

2 portions is `movable outwardly into engagement with the casing in response to relative movement of the upper and lower housing members toward one another. The remaining end of the packer is coupled to the upper housing member so that the packer element may be compressed into engagement with the casing in response to relative movement of the upper housing member towards the slip means. Friction means for engaging Vthe casing are carried by the lower housing member. By-pass port means are arranged to be closed within the housing assembly in an intermediate position of the mandrel assembly relative to the housing assembly. Downward movement of the mandrel assembly is transmitted to the upper housing member by a pair of engageable shoulders arranged to engage in an intermediate position of the mandrel assembly relative to the housing assembly to set the slip means and compress the packing element into engagement with the casing in a sequential operation. Releasable locking means are provided to lock the mandrel assembly to the housing assembly in the spaced longitudinal positions. The upper housing member of the packer may be provided with hold-down slip means to provide an additional resisting force when higher pressure differentials below `the packer acting upwardly thereon tend to slide the packer upwardly in the casing. A safety joint mechanism to release free portions of the packer from stuck portions thereof may also be employed with the device.

Other features of the invention and other of its objects and advantages may be perceived from the following detailed description when taken in conjunction with the accompanying drawings in which:

FIGS. la and 1b are views in lo-ngitudinal cross section of the upper and lower portions, respectively, of a well packer constructed in accordance with the invention and shown in its going-in or open position;

FIGS. 2, 3, 4, 5 and 6 are cross-sectional views of the apparatus of FIGS. la and lb taken on the lines 2 2, 3 3, 4 4, 5 5 and 6 5, respectively, looking in the directions of the arrows shown;

FIGS. 7a and 7b are elevational views of the upper and lower portions, respectively, of the packer, portions thereof being shown in section and a portion ofthe housing being broken away to show the mandrel cam splines;

FlG. 8 is a sectional view of a portion of the apparatus of FIG. 7 showing the hold-down slip means in set posi- FIGS. 9a and 9b are elevational views of the upper and lower portions, respectively, of the preferred embodiment of the packer, portions thereof being shown in section, the tool being illustrated in the going-in position; and

FIGS.' 10a and 10b are views similar to the views of FIGS. 9a and 9b showing the packer in a setting position.

Referring to FIGS. 1a and 1b, a well packer 10 constructed in accordance with the principles of this iuvention is shown in an operating condition for going into a well casing or bore wall 11. The packer 10 comprises generally a tubular housing assembly 15 extending substantially the full length of the device within which is received, for limited longitudinal and rotational movement relative thereto, la tubular mandrel assembly 16 which extends completely through the housing assembly and projects upwardly of the upper end of the housing assembly. The housing assembly 15 includes an upper housing section 17 (FIG. la) and a lower housing section 18 (FIGS. la and lb). The upper housing section 17 includes subs 5S, 56 which form an upper or rst housing and an elastomer packer element 20, a sleeve 58 connected to sub 56 and on underlying element 20 an expander 6i). Sleeve 58 and expander 60 are telescopicallyl connected to one another so that when the subs 55, 56 and the expander move relatively toward one another,

the packer element is compressed longitudinally and expanded outwardly into engagement with the casing or bore to pack off that portion of the annulus therebelow. The expander 60 has slips 115 connected thereto which are linked to the lower housing section section 18 so that relative movement between the expander and housing section 18 causes the slips `to move outwardly into engagement with the casing. Housing section 18 includes a tubular friction pad member 110, a tubular split nut retainer member 111 and a tubular retainer member 112 which form a second or lower housing member.

The mandrel assembly 16 is concentric with the housing assembly 15 and has an uppermost sub 30 and mandrel sections 31 to 34 which rare threadedly secured together in end-to-end relationship to define a continuous bore 35 extending throughout the length of the packer 10 for the passage fo fluid. Sub 30 is threadedly secured at its uppermost end to a tubular sub carried by a tubing or drill string and is movable therewith. The packer 1t) may be used with or without a drill stem testing tool above it. In an exemplary arrangement for use with a testing tool, `the sub 40 carried by a tubing or drill string may contain a recorder, for example, as disclosed for use with a full opening formation tester which is described in an application by the present inventor, Serial No. 775,023, tiled November 19, 1958, and assigned to the assignee ofthe present invention.

Sub 30 has a lower edge which defines a downwardly directed shoulder 41, and the sub 30 is iluidly sealed to the top mandrel section 31 by means of O-rings 42. Immediately below the shoulder 41 is an annular packing sleeve 45 containing longitudinally spaced and oppositely `directed chevron-type seal rings 46 and 47 which are well known in the art. To provide a iuid by-pass through the packer 10 to the well annulus above the packer as the packer is going into the borehole, a plurality of by-pass ports 48 extend laterally through the top mandrel section 31 below the packing sleeve 45.

Mandrel section 31 has a lower box end 49 which is diametrically enlarged to define an upwardly facing shoulder 50. As can be seen in FIG. 7a, the downwardly exposed shoulder of section 31 is formed with at least one cam groove 51. In the preferred arrangement illustrated, four adjacent cam grooves each including an inclined portion 52 and an axially extending locking portion 53 are provided. As will subsequently be more clear, cam grooves 51 provide a positive lock against torque in one direction.

The upper edge of the packing sub 55 defines an upwardly facing shoulder 63 arranged to be engageable with the shoulder 41 on the sub 30 thereby limiting downward travel of the mandrel assembly 16 relative to the upper housing section 17 and to allow further downward motion of the mandrel assembly 16 to be transmitted -to the housing section 17. The sub 55 also has a lower pin end 66 extending into sub 56 having a lower edge defining a downwardly facing shoulder 67 engageable with the shoulder on mandrel section 31 to limit upward travel of the mandrel assembly 16 relative to the upper housing section 17.

he bore 79 extending through the sub 55 has a reduced diameter portion 71 which slidably receives a portion of the mandrel section 31 between the packing sleeve 45 and the shoulder 50. The bore 70 is sized to receive the packing sleeve 45 for providing a tiuid seal between the sub and mandrel section 31 and, thus, as the mandrel assembly 16 is moved downwardly, the packing sleeve 45 enters the bore 70 and the seal rings 46 and 47 pack off the sub 55 and mandrel section 31. By-pass ports 48 below the packing sleeve 45 are consequently closed so as not to receive any borehole tiuid.

The hold-down sub 56 has an upper bore portion 75 loosely receiving the enlarged box end 49 of mandrel section 31 for movement therein. Bore 75 extends to a concentric lower bore portion 76 of smaller diameter which slidably receives the upper intermediate mandrel section 32. Within respective openings 79 in lower end 78 of sub 56 are a plurality of hold-down slips 30 operative in a manner to be hereafter explained. As shown in FIG. 2, each of the slips 30 comprises a block of metal having an outward cylindrical face 81 which is grooved longitudinally and provided with laterally-extending upwardly-tapering serrations 32, best seen in FIG. la. A seal ring S5 disposed with in peripheral groove in each of the slips 30 engages the wall of its respective opening or cavity '79 to prevent fluid flow outwardly around the edges of the slips 80. Upper and lower leaf springs and 91 for each of the slips 30 are appropriately secured to the lower sub end 78 and their free ends engage opposite end portions of the slips. These springs resiliently bias slips Si) toward retracted positions within their openings 79.

Extending radially through the housing sub 56 near the lower end of the upper bore 75 are pins 86 which are threadedly received in the housing sub 56. These pins cooperate with cam grooves 51 in effecting a locking action for the tool in a manner to be more apparent from the discussion to follow.

An upper packing shoe 57 is threaded to the outside of the lower end of housing sub 56, while a packer sleeve 58 is threaded to the inside of the sub 56. The packer sleeve 5S slidably carries the annular packing element 20, which is made of an appropriate elastomer material. The lower end of upper shoe 57 includes an inwardly projecting iiange S8 terminating in an annular surface which engages the outer surface of packer sleeve 58. Flange S8 has a lower surface 89 which includes a downwardly and outwardly sloped surface from the center of the tool and a surface curving upwardly to the outer surface of shoe 57.

The upper edge of the elastomer packing element 20 is complementarily shaped in order to inhibit plastic flow of the elastomer material when compression is applied. A lower packing shoe 59 engages the lower surface of the packing element 20, and the interengaging faces thereof are similarly shaped as surface 89, only oppositely arranged to inhibit plastic tiow of the elastomer material at the lower surface. Lower packing shoe 59 is threaded to a slip bowl or expander 60 and has a rim 92 which extends toward sleeve 58 and terminates in an annular surface 93 slidably engaging the sleeve 58. A seal ring 94 is an annular groove in the upper end of sleeve 58 iiuidly seals the lower end of sub 56 preventing fluid ow between the sub 56 and the sleeve 58.

Inner bore 95 of the expander 60 defines an annulus 96 between the expander 60 and the upper intermediate mandrel section 32 for receiving the end of the packer sleeve 58 when the packing element 20 is compressed. The outer surface of the expander 60, as is conventional, has a plurality of downwardly and inwardly inclined at surfaces 98 having dovetail portions 99, best seen in FIG. 3. The lowermost edge 100 of the expander is engaged, when the mandrel assembly 16 is in its uppermost position, by an upwardly facing shoulder 101 defined by the uppermost edge of the lower intermediate section 33.

The packer sleeve 58 is keyed to the expander 60 to be co-rotative therewith while allowing longitudinal movement relative thereto when the packing element 20 s being compressed. To this end, the lower end of sleeve 58 is provided with a pair of diametrically opposite rectangular keys 105 (see FIG. 4) and the bore 95 of the expander 60 is formed with two diametrically opposite keyways 106 each slidably receiving one of the keys 105.

The lower housing section 19 (FIG. lb) is comprised of the tubular friction pad mounting member 110 and the tubular split nut retainer member 111 and a tubular bottom retainer member 112, the members being threadedly coupled to one another in an end-to-end relation. A plurality of serrated casing slips 115 on the expander 60 are connected to the lower housing section 18. Each of the slips 115 has an upwardly and outwardly inclined inner surface 116 and a dovetail portion 117 to mate with one of the expander surfaces 98 and dovetail portions 99. The outer cylindrical surface of the slips 115 have downwardly tapered lateral serrations 118 to grip the casing and also have a plurality of longitudinally extending grooves 119. The lower ends of the` slips 115 are pivotally secured to upper ends of the member 110 for outward motion relative thereto by linkage or pivoted rein connections 122. Thus, as the expander 66 moves downwardly, the slips 115 are wedged outwardly into engagement with the casing.

As best seen in FIG. 5, the friction pad member 116 has a plurality of scooped-out portions defining a numher of at mounting surfaces 126. Mounted on each surface 126 is a conventional friction pad assembly 127 comprising a mounting plate 128 to which is fastened a flanged retainer 129. Each retainer receives a wall-engaging pad 130 which is biased outwardly; the thickness of the pad assembly is chosen so as to slidably, `yet frictionally, engage the portion of the casing where the packer is to be used. In the embodiment illustrated, three such equaily-spaced pad assemblies are provided.

Between the members 11? and 111 and between the members 111 and 112 are a pair of similar but oppositely directed wedge constructions 132 and 133, respectively. Wedge construction 132 includes a cylindrical bore 134 in the upper box end of section 111 and a connecting, inwardly and upwardly sloping, frustoconical wedging surface 135 in the pin end of member 110 which terminates in a downwardly facing shoulder 136. Wedge construction 133 includes a cylindrical bore 140 in the lower box end of section 111 and a connecting downwardly and inwardly sloping frustoconical surface 141 in member 112 terminating in an upwardly facing shoulder 142.

A left-hand split nut 145 and a right-hand split nut 146 are received between the respective wedge constructions 132 and 133 and the mandrel assembly 16. Split nut 146 has an external surface including a frusto-conical surface 147 having the same slope as surface 141 and a cylindrical portion 148 having a diameter less than that of bore 145. The interior surface of the split nut 146 is provided with a plurality of upwardly pitched righthand threads 155 to mate with a series of complementary right-hand buttress threads 151 on the upper end of the bottom mandrel section 34.

Split nut 146 is arranged to oe contractible to threadedly engage the mandrel threads 151 as when in the open position of FIG. lb and to enable ratcheting of the threads 151 through the split nut 146 as when moving from the set position of FlG. 7b back to the open position of FIG. lb. To this end, referring to FIG. 6, nut 146 has a plurality of grooves 152 in its outer surface and has a slot 153 which extends completely through it in both longitudinal andradial directions. As pin 154 is fixed to the lower box end of member 111 and extends into the bore 140 within the slot 153 to prevent relative rotation between the nut 146 and lower housing assembly 18 while allowing limited longitudinal movement relative thereto. The pin 154 is sufficiently narrow to allow contraction of the nut 146 into mating engagement with the threads 151. This contraction occurs when the sloping nut surface 147 is wedged inwardly by the complementary sloping surface 141 until limited by the contact of the lower edge of the nut 146 with housing shoulder 142. As can be seen in FIGS. la and lb, the full engagement of the threads 150 and 151 locks the mandrel assembly 16 to the housing assembly 15 to prevent down-` ward movement of the mandrel assembly within the housing assembly when the packer is in the going-in or open position. Y The split nut 145 has an external frusto-conical surface 160 having the same slop as wedge surface 135 and a cylindricalv external surface 161 having a diameter less than that of bore portion 134. The internal surface of the nut is provided with a plurality of downwardly pitched left-hand threads 162. In similar fashion as nut 146, the nut 145 is grooved and slotted through completely to receive a pin 165 fixed to the member 111 and extending into the bore 134. Thus, nut 145 is co-rotatively secured to lower housing section 18 but has longitudinal freedom to move upwardly until stopped by engagement with housing shoulder 136, the wedging action of the surfaces 135 and 160 contracting the nut as upward movement proceeds.

The lower intermediate mandrel section 33 i carries, toward its upper end, a plurality of upwardly pitched lefthand buttress threads lcomplementary to the threads 162. As will subsequently be more clear, the threads 162 and 170 are engaged when the packer is set to lock the mandrel assembly to the housing assembly. The bore 172 of member 11) and the bore 173 of member 111 have a diameter sufficiently large to freely pass the buttress threads 170 as they move into and out of engagement with the nut 145.

In an exemplary operation of the multiple purpose casing packer 18, the packer is assembled at the surface at the end of a tubing string or below a drill stem formation tester or other valve with the various parts in the relation shown in FIGS. la and lb. In this condition, mandrel assembly 16 is locked against downward movement within lower housing section 18 by the engagement of the right-hand mandrel threads 151 with the threads 150 on right-hand split nut 146. The nut 146 is in its lowermost position within the wedge construction 133 engaging the shoulder 142. Because of the wedging action of the downwardly and inwardly sloping frusto-conical surfaces 135 and 162, full engagement of the threads 150 and 151 is attained and further downward movement of the mandrel assembly 16 merely increases the locking action by increasing the inward wedging force.

In the going-in or open position, the by-pass ports 48 are exposed to the drilling fluid. Drilling fluid thus passes upwardly through the mandrel bore 35 and laterally outward through the ports 48 to the well annulus thercabove. At this point in a cycle of operation, the casing slips 115 are retracted out of engagement with the casing wall and are held in a retracted position while the tool is going in by means of engagement of thek mandrel shoulder 101 with the lower edge 100 of the expander 60. If the tool is raised the packing element 20 remains uncompressed by virtue of mandrel shoulder 50 in engagement with the lower edge 67 of housing top sub 55. Thus it is seen that pushes and pulls as might be experienced by the packer 16 while going in are ineffective to set the slip means 19 or elastomer packing element 20 or to close the by-pass ports 48. Positive rotation to release the threads 15u and 151 is required before the packer can be set as will hereinafter become more apparent.

When the packer is at a selected level in the casing 11 where it is desired to obtain a pack-off, the packer is set by initially rotating the tubing string to the right and simultaneously lowering it. Lowering is necessary to prevent the right-hand split nut 146 from jumping threads,

inasmuch as the nut is biased to expand on the removal ofv By lowering the tubing string as rotation proceeds a downward force is exerted on the inward wedging forces.

split nut causing the inwardly sloping surfaces 141 and 147 to apply an inward force on the nut causing it to contract. With the exception of the slot 153, the split nut 146 then forms perfect threads and enables the mandrel assembly 16 t0 be screwed through it. The pin 154 is suiciently thin to permit contraction of the split nut and keys the split nut to lower housing section 18 to prevent rotation therebetween. Since the friction pad assemblies 127 engage the casing and restrain rotation of the housing assembly 15, the mandrel assembly is the only part which rotates.

When the threads 150, 151 disengage, the mandrel as-V sembly 16 is free to move downward within housing assembly 15. The by-pass ports 48 close as the seal rings 46 and 47 pack-off inside top sub 55. When the shoulder 41 on connecting nut 30 engages the upper edge 63 of upper housing section 17, further downward motion of the mandrel assembly 16 is transmitted to the upper housing sections 17, and this section moves relative to the lower housing 1S which resists longitudinal movement because of the contact of the friction pad assemblies 127 with the wall of the casing. Thus, downward movement is transmitted through the upper housing section 17 to the expander 60, and the inclined surface 9S thereon slides relative to the inclined face 116 of the slips 115 to wedge the slips 115 outwardly into gripping contact with the casing.

Motion of the expander 6i) and attached lower packer shoe 59 now ceases and further downward motion of the mandrel assembly serves to compress the elastomer packing element 2). During this compression, subs 55, 56, 57 and 58 move downwardly as movement is transmitted to these subs by the engaging shoulders 41 and 63 and the packer sleeve 5S telescopes into the annulus 96 of the slip cage 66. The packing element 20 expands diametrically into engagement ith the casing and the packer is now in the set position of FIGS. 7a and 7b.

During the downward travel of the mandrel assembly 16, the mandrel buttress threads 170 ratchet through the upper leftliand split nut 145. The split nut 145 acts in the opposite direction from split nut 146 in that an upward pull on mandrel 16 will not produce movement thereof relative to housing assembly 15. This is because the wedging action of the inclined faces 135 and 160 contracts the split nut 145 and produces a locking engagement between the threads 170 and 162. Upward motion of the mandrel assembly 16 when the packer is set is therefore limited by the engagement of the upper edge of the split nut 145 with the housing shoulder 136. A greater number of threads 170 are provided than threads 162 to assure a connection for various sizes of drill pipe which will vary the length of travel of the section 32.

The locking of the mandrel assembly 16 to the housing assembly when the packer is set is advantageous in several respects. First, an upward pull on the mandrel assembly cannot open the by-pass ports 48 or tend to unseat the packer. This is particularly useful when running the packer in conjunction with an auxiliary valve such as a formation tester which requires tension to be applied to the tubing string to operate the valve. Furthermore, the differential pressure produced while acidizing, uid fracturing and squeeze cementing will not force the mandrel assembly 16 upward relative to the housing assembly to open the 'oy-pass valve.

A higher pressure within the bore 35 of the mandrel assembly 16 than in the well annulus outside the tool, such as is the case when acidizing, fluid fracturing and squeeze cementing, causes the hold-down slips 80 to move outwardly against the resistance of leaf springs 90 and 91 into gripping contact with the casing. The pressure so produced is applied through the port 48 to the annulus between housing sub 56 and mandrel sections 31 and 32 and then to the back and sides of the slips 80 as far as the Sealing rings 85. The outward force on the hold-down slips causes the upwardly tapered teeth 82 to grip the casing (see FIG. 8) with a force which is directly proportional to the pressure differential and provides a resisting force which prevents the packer from moving up in the casing. When the pressure across the hold-down slips 80 is equalized, the leaf springs 90 and 91 return the slips to their retracted position within sub 56. Should the leaf springs not supply adequate restoring force, the slips may be retracted by reversing the pressure differential on them, i.e., by increasing the pressure in the well annulus.

To unseat the packer, it is necessary to first release a the threaded engagement between the split nut and the mandrel assembly 16. This is accomplished by rotating the tubing string to the right and simultaneously exerting a pull thereon. The nut 145 is wedged inwardly by the inclined housing surface 135 and forms a perfect thread with the exception of the slot therein. The pin co-rotatively keys the nut 145 to the lower housing section 18 as the relative rotation proceeds. Right-hand rotation of the mandrel and cam grooves 51 relative to the pins S6 is permitted by the tapered surface 52.

When disengaged, the mandrel assembly 16 is pulled upwardly to retract the seal rings 46 and 47 from within the bore 72 and expose the by-pass ports 48 to the well fluid, thereby equalizing the pressure above and below the packer. Continued upward travel of the mandrel assembly engages the mandrel shoulder 50 with the lower edge 67 of the upper housing top sub 55. Thereafter upward motion of the mandrel assembly is transmitted to the upper housing section 17 to exert tension on the packer element 20 and return it to its uncompressed original shape. At about this stage the shoulder 101 on the mandrel section 33 contacts the lower edge 100 of the expander 69 and the slips 115 are retracted due to the tapered dovetail connection 99, 117 between the slips and expander. During this final movement, the mandrel buttress threads 151 ratchet back through the uncontracted lower split nut 146. The packer may now be retrieved from the well.

Should the wall-engaging portions of the packer fail to unseat properly, a conventional left-hand, safety joint means in the well string may be operated by left-hand rotation of the tubing string. The surface 53 of mandrel cam grooves 51 are first engaged with the pins 86 to lock the mandrel with respect to the housing sub 56 so that further rotation will unscrew the safety joint.

The casing packer 10 constructed in accordance with the principles herein set forth is particularly suited for a sequence of operations involving testing, acidizing, fluid fracturing and squeeze cementing or any combination of them. Once set, the packer cannot be unseated by simply pulling on the mandrel and it is provided with a locking means and hold-down slip means to resist upward forces on the mandrel and packer resulting from higher pressures from below. The packer 10 also has the usual slip means and elastomer packing element arranged to resist downward unseating forces from above, such as by the pressure diterential produced when testing.

While especially suited for the sequence of operations cited above, particularly when used in cooperation with the full opening testing tool described in the aforementioned patent application, the packer 10 may be used as desired without a testing tool and may be used in any operation for which its structure adapts it.

The packer 10 is full opening to allow lowering a gun perforator or other small diameter well tool through the mandrel bore 35. This bore 35 is also advantageously large in order to enable treating with large fluid volumes.

Turning now to another embodiment of the present invention wherein similar parts are numbered correspondingly to the parts of FIGS. l-8, a casing packer 180 is shown constructed in accordance with the principles of the present invention, however, employing a preferred hydraulic hold-down arrangement 181 and manipulating screw-threaded mechanism 182.

Referring now generally to FIGS. 9a and 9b, packer has an outer tubular housing assembly which includes an upper housing section 17 and a lower housing section 18. Upper housing section 17' includes tubular members or subs 184, 185, 186, and a packer shoe 187, member 186 being coupled to one end of a packer element 20 while the remaining end of the packer element is coupled to an expander 60. Expander 60' has slips 119 which are linked to the lower housing section or member 18. The expander 60 and slips 119 `generally comprise slip means 19. Slidably received within the housing assembly is a tubular mandrel assembly 16' which is adapted to be coupled to a pipe string, the mandrel assembly 16 extending completely through the housing assembly.

Mandrel assembly 16' includes a top sub 30 and Inandrel sections 31', 32', 33" and 34', and 183 which are threadedly connected in an endto-end relationship. A continuous central bore 35 extends through the mandrel assembly 16 for passage of fluid. Sub 30 is threadedly secured at its upper end to a recorder member 40 and is movable therewith. Member 40 is arranged to be coupled with the drill string (not shown).

The housing section 17 extending lengthwise of the mandrel assembly 16 includes a top sub 184, an intermediate sub 185, a slip housing sub 186, and an upper packer shoe 187 which are suitably threadedly connected together. A slip actuating sleeve or expander 188 is slidably received within an annulus formed between subs 184, 185, 185 and mandrel sections 31', 32. Further included in section 17' is an elastomer packing element 26 bonded to the upper shoe 187 and to lower packer shoe 189 and slidably supported by a packer sleeve 190 which is connected to the upper shoe 187 and slidably and sealingly supported on the mandrel section 3S. The lower shoe 189 is threadedly connected to an expander 60' which is suitably keyed to slips 115. Slips 115 are connected by a link and pin connection 122 to housing sub 191 of housing section 18. Sub 191 contains split nuts 192, 193 which cooperated with threaded portions of mandrel section 34', 183, respectively. rl`he remainder of housing section 18' includes threadedly coupled subs 194, 195.

As shown in FIG. 9a, the lower end surface 41 of sub 3i? forms a square shoulder which limits the downward travel of the sub upon engagement with the upper end surface 196 of housing sub 184. Disposed below surface 41 in the mandrel assembly are a plurality of lateral by-pass ports 48 which place bore 35 in uid communication with the exterior of the tool or with a hydraulic chamber 197 in the housing as will become more apparent later. Sealing rings 46', 47 are disposed above the ports 48 while sealing rings 198 are disposed below the ports 48. Mandrel section 31 is adapted to be slidably and sealingly received in the central bore 199 of sub 18d. Top sub 18d and housing sub 185 have, respectively, a counterbore 2% and a central bore 2131 of similar diameters which threadedly receive the pin ends of sub 185. Sub 135 is provided with a reduced diameter central bore 202. Slip actuating sleeve 188 is slidably received within the annulus deiined by the bore 206, 202, 2111 and mandrel sections 31', 32.

The slip actuating sleeve 188 includes a lower annular body portion 263 which is slidably received between the bore 2111 and mandrel section 32 having a counterbore 204 therein, an intermediate stem portion 255 which is stepped inwardly of the sub bore 201 so as to be slidably received in sub bore 202 and limited in upward movement by the end shoulder of sub 185, and an annular piston member 256 slidably received between sub bore 202 and mandrel section 31 and being threadedly connected to the stem portion 2&95. The lower end portion of mandrel section 31' has grooves 267 extending lengthwise of the section from a point below the lower seal 198 to the end surface and also has outwardly extending splines 203 at its lowermost end which are slidably received in the counterbore 204 and limit the downward movement of the piston member 206.

Pressure chamber 197 includes the counterbore 200 of sub 18d, the piston member 206 and mandrel section 31'. When the ports 48 are placed in iluid communication with chamber 197, seals 46', 47 and 198 tiuidly seal the piston 206 for movement on section 31 while a seal ring 2629, such as an O ring fluidly seals the piston 2116 in the bore 202. (FIG. 10a.)

Slips 80 are contained in windowed apertures in sub 186 and have outer serrated edges to grip the casing. The inner surface of slips 80 have dovetail keys which are complementarily received in dovetail keyways in a tapered outer surface of the lower portion 203 of expander 188. The tapered surfaces permit the slips 86' to be cammed outwardly when the expander 188 is moved in a downward direction. The lower end of sub 186 has an inwardly extending llange 210 and therebelow a threaded bore to receive the pin end of the packer shoe 187. The ange 210 and inner shoulder of the pin end form a recess which receives an outwardly extending flange 211 of the tubular packer sleeve 19t). Packer sleeve 190 slidably supports the annular elastomer packer element 20 and is slidably received at its lower end in the central bore of the lower packer shoe 189. Mandrel section 32' has an enlarged portion 212 having a diameter portion sized to the central bore of sleeve 190 and having an 0 ring to uidly seal the portion 212 with respect to the sleeve 190.

Lower packer shoe 189 is threadedly connected to one end of the expander 66. The opposite end of expander do has a central bore arranged to be slidably mounted on mandrel section 35. A counterbore 95 in expander 61) defines an annular space between the expander 60 and the mandrel section 35 for receiving the end of the packer sleeve 1915 when the packing element 20 is compressed. The lower, outer surface of the expander 60 is conventional having a plurality of downwardly and inwardly inclined at surfaces 98 with dovetail keyways which receive dovetail keys of the complementary tapered surface of slips 115. Pins 213 mounted in the expander 60 perpendicular to the tapered surface slide within grooves in slips and are arranged to limit the eX- pander 68 from moving in an upward direction. The lower end surface 215 of expander 6G bears against the end shoulder of mandrel section 34' in the collapsed posi` tion of the packer element 2t). Slips 115 have outer serrated surfaces and are connectedby a pin and link connection 122 to the sub 191 of lower housing section 18'.

Disposed in recesses 216 of the sub 191 below the link connection 122 are friction pad assemblies 127 which have heretofore been described. A central bore 217 extends through sub 191 and the lower sub 195 which slidably receives mandrel sections 3d', 183, respectively. 0 rings 218 providing a wiping action are disposed between the surfaces. Sub 191 has enlarged, stepped counterbores 219, 22@ at its lower end which respectively receive split nuts 192, 193. The downwardly facing shoulderbetween bore 217 and counterbore 219 serves to prevent upward movementof split nut 192. The lower end of counterbore 220 threadedly receives the pin end of sub 194 thereby presenting an upwardly facing shoulder to prevent downward movement of split nut 193. SplitV nuts 192, 193 are comprised of a plurality of internally threaded segments which are resiliently held together for axial expansion and contraction by spring collars 221 and are prevented from longitudinal and torsional movement by pins 222 which extend into axial bores in the segments and are secured in axial bores in the sub 191.

Split nut 192 has left-hand threads which are arranged complementary to left-hand threads disposed on an upper recessed portion of mandrel section 311'. Threads 17? are arranged to be movable through bore 217 in downward direction until ratcheted into engagement with split nut 192. Split nut 193 has right-hand threads which are arranged complementary to right-hand threads on an upper enlarged portion 223 of mandrel section 183 which is threadedly connected to mandrel section 34. In the going-in position of the packer, as shown, the portion 223 is in threaded engagement with the split nut 193. Sub 194 has an enlarged central bore 224 which permits longitudinal movement of the threaded portion 223 there- In an exemplary operation of the packer 180, the packer is assembled as in FIGS. 9a-9b and lowered by means or" a drill string to the level desired for setting the packer.

In lowering, the mandrel sections 31', 32', 33', 3ft and 183 are directly connected to the lower housing section 13' by means of the threaded end portion 223 and the split nut 193 which bears against the upwardly facing shoulder of sub 194. By-pass ports 43 are open to permit passage of the well fluid through the packer bore 35 while it is lowered in the well. Casing slips 115 are retracted and cannot be expanded until the threaded portion 223 is released from split nut 193 since a relative movement between the mandrel assembly 16' and housing section 18 is required to set the slips. Slips Sii are also retracted since the piston member 206 of the slip actuating sleeve 188 is held against downward movement by engagement with the upwardly facing shoulder of the splines 20S on the mandrel section 31. lt will hence be appreciated that neither upward nor downward movement of the packer in a borehole will permit setting of the slips 80 or 115.

To set the pack r 18?, the pipe string is rotated to the right. The housing assembly is frictionallf.I held by pads 127 against movement and the threaded portion 223 of the mandrel section 183 is screwed out of the split nut 193 whereupon the mandrel assembly may be moved downwardly relative to the housing assembly permitting the slips 115 to be set in the casing. ln particular as shown in FIGS. a and 10b, the downward movement of the mandrel assembly causes end surface 41 of sub 30 to engage surface 191 of housing sub 134 and the upper housing section 17 is forced downwardly transmitting force through the housing subs and packer element to the expander 69 which causes the slips 115 to be cammed outwardly into engagement with the casing wall. When slips 115 grip the wall with sufiicient force the packer element 20 is caused to expand into sealing engagement with the casing wall. During the downward travel, threads 17@ on the mandrel assembly ratchet and engage with the threads of split nut 192 and serve to lock the mandrel assembly 16 against any return upward movement thereby precluding any unseating of the packer due to upward pulls. By-pass ports 48 have also been positioned in the top sub 184 so that they open into the annular chamber 197 and are fiuidly sealed in bore 199 and piston member 265 by seals 46', 47' and 198.

When higher pressures are introduced in the bore of the mandrel assembly, the pressured iiuid passes through ports 48 to force the piston 200 downwardly causing the expander 188 to cam the slips 8a into engagement with the casing. Hence the packer element 20 is secured above and below by slips 80 and 115.

To unseat the packer, rotation to the right and pulling up on the mandrel assembly will cause the left-hand threaded connection between threads 174) and split nut 212 to be disengaged and permit the mandrel assembly to be pulled upwardly. In upward movement, the recessed portion 207 of mandrel section 31' permits any iiuid contained in the annular chamber 197 to escape while the upwardly facing shoulders of splines 208 engage the lower surface of piston member 260 raising it upwardly thus returning expander 183 and slips 89 to their original position. Further upward movement unseats packer element 20 and expander 60" moves upwardly so that slips 115 are returned to their original position. During this final movement the threaded end portion 223 re-engages split nut 193 and the packer 180 is thus returned to its original position. The packer may then be retrieved or set at a different level in the borehole.

While particular embodiments of the present invention have been shown and described, it is apparent that changes and modifications may be made without departing from this invention in its broader aspects, and therefore the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of this invention.

What is claimed is:

1. A full-opening packer for setting in a wel] bore or casing comprising: an outer housing assembly including a first tubular housing member, an elastomer packing element, slip means, and a second tubular housing member, said slip means including relatively movable portions thereof respectively connected to one end of said packer element and to said second housing member, one of said portions being movable outwardly for gripping engagement with the walls of the well bore in respouse to relative longitudinal movement of said packer element and said second housing member toward one another, the remaining end of said packer element being secured to said first housing member whereby relative movement of said first housing member towards said slip means expands said packer element outwardly of said assembly; wall-engaging friction means fixed to said second housing member; an inner tubular mandrel assembly received by said outer housing assembly for limited relative longitudinal movement therein between upper and lower longitudinally-spaced positions; engageable shoulders on said inner mandrel assembly and said first housing member arranged to engage when said inner mandrel assembly is intermediate of one of said positions whereby engagement of said shoulders serves to permit movement of said first housing member and said packer element relative to said second housing member to set said slip means and thereafter permit movement of said first housing member relative to said slip means to compress said packer element; rst threaded means coupled between said mandrel assembly and said second housing and releasably locking said mandrel assembly against longitudinal movement relative to said second housing in said upper position; and second threaded means coupled between said mandrel assembly and said second housing and releasably locking said mandrel assembly against longitudinal movement relative to said second housing in said lower position, said first and second means being threaded in opposite directions.

2. The apparatus as claimed in claim l wherein said iirst releasable means includes a split nut mounted in said second housing member and having an internal lefthand thread, said second releasable means includes a split nut mounted in said second housing member and having an internal right-hand thread, and said mandrel assembly has an upper left-hand threaded portion and a lower right-hand threaded portion which respectively cooperate with said split nuts to releasably lock said mandrel assembly to said second housing member in said upper and lower positions.

3. The apparatus as claimed in claim 2 wherein said split nuts are comprised of a plurality of arcuate segments, said apparatus further including snap rings to resiliently maintain said segments in spatial relationship to one another and key means between said segments and said second housing member to prevent rotation of said segments.

4. The apparatus as claimed in claim l and further including bypass port means in said inner tubular assembly arranged to be open to the well bore in said upper longitudinal position and to be closed within said outer housing assembly in said lower longitudinal position; and holddown slip means in said rst housing member including hydraulic pressure cylinder and piston means responsive to higher pressures within said mandrel assembly applied via said port means to actuate said slip means and secure said iirst housing member relative to the well bore.

5. The apparatus as claimed in claim l and further including bypass port means in said inner tubular assembly arranged to be open to the well bore in said upper longitudinal position and to be closed within said outer housing assembly in said lower longitudinal position; and hold-down means in said first housing member including relatively movable portions, one of said portions adapted to engage the wall of the borehole and the other of said portion forming an annular piston in a recess between said mandrel assembly and said first housing member, said bypass ports being placed into fluid communication with said piston whereby iluid pressure may actuate said hold-down means.

6. The apparatus as dened in claim 1 wherein said iirst and second releasable locking means includes a pair of oppositely threaded split nut arrangements and wedging surfaces in said second housing member for locking said mandrel assembly to said second housing member in said upper and lower positions.

7. The apparatus as deiined in claim l wherein said first and second releasable locking means includes a pair of longitudinally-spaced and oppositely-sloping internal -wedging surfaces in said second housing member, a pair of longitudinally-spaced external threaded sections on said mandrel assembly, a pair of split nuts each having an external wedging surface engageable with one of said housing member wedging surfaces and having internal threads independently engageable with one of said mandrel assembly threaded sections, and means keying each said split nut to said second housing member to prevent rotation while permitting relative longitudinal movement. a

8. The apparatus as defined in claim 1 wherein said first and second releasable locking means further includes a pair of oppositely-directed bowl-shaped wedging surfaces in said second housing member, a pair of opposite'lythreaded split nuts each co-rotatively secured to said second housing member and received between one of said bowl surfaces and said mandrel assembly, each said split nut having an inclined wedging surface engageable with a correspondingly inclined surface in said second housing member, and a pair of longitudinally-spaced buttress threaded sections on said mandrel assembly, one of said threaded sections being threadedly engaged with one of said split nuts when in said upper position and the other of said threaded sections being threadedly engaged with the other of said split nuts when in said lower position.

9. A packer for setting a well bore or casing comprising: a full-bore tubular mandrel assembly adapted for connection Vat its upper end to a well string; a tubular housing assembly interitted about said mandrel assembly for limited relative sliding movement thereaiong, said housing assembly comprising an upper housing section including an upper housing member, a packing sleeve secured to said housing member, a slip expander telescopically connected with said packing sleeve for limited downward movement with respect thereto, a packer element supported by said sleeve between confronting por- .tions of said upper housing member and said expander for expansion thereby, and slips slidably secured to said expander; and a lower housing section including friction means for engaging the well bore or casing connected with said slips to permit them to move between expanded upper and contracted lower positions relative to said expander; said mandrel assembly and said lower housing section having releasably interengageable portions to restrict upward movement of said slips relative to said mandrel assembly until released; said mandrel assembly and said housing `assembly further having abutment portions engageable with one another limiting downward movement of said expander to prevent expansion of said slips until said abutment portions are disengaged by release of said releasably interengageable portions; said mandrel assembly having upwardly directed threaded .ratchet teeth therealong; said lower housing section having a threaded ratchet sleeve slidable over said ratchet teeth upon movement of said slips relative to said expander to their expanded upper portion for releasably engaging said ratchet teeth to Ilock said slips in their expanded upper position and releasable by unthreading said mandrel assembly from said lower housing section.

References Cited in the tile of this patent UNTED STATES PATENTS Baker et a1. Sept. 17, 1957 Reed Sept. 9, 1958 

